COPPER RIVER WATERSHED HABITAT ENHANCEMENT PROJECT In Cordova, Alaska ...

[Pages:13]COPPER RIVER WATERSHED HABITAT ENHANCEMENT PROJECT In Cordova, Alaska

Discussion of Geotechnical and H&H (Hydraulic and Hydrologic) Reports

Teleconference Meeting Meeting Minutes

Date: March 5, 2019; 9:00 a.m.-11:00am

Purpose of meeting: Discuss and review comments on the Draft Geotech for all crossings and H&H Reports for Cop 43, 44, & 45 (20100508, 20100510, 20100511)

Location:

Teleconference: (877) 620-0608 Passcode: 12345654321

Attendees:

Name Heather Hanson Franklin Dekker Gillian O'Doherty Erika Ammann Theresa Tanner Dan Adamczak Jeff Stutzke John Bennett Steve McGroarty Chantel Adelfio Kristin Carpenter Kirsti Jurica Kate Morse Bill Spencer

Agency/Company USFWS, PM USFWS ADF&G NOAA USFS ADOT&PF ADOT&PF ADOT&PF ADOT&PF CRWP CRWP CRWP CRWP HDR

Kyle Walker

HDR

Contact Info (907) 271-1630 Franklin_dekker@ Gillian.odoherty@ erika.ammann@ theresatanner@fs.fed.us daniel.adamczak@ jeff.stutzke@ Johnd.bennett@ Steve.mcgroarty@ kate@ kristin@ juricaka@ kate@ (907) 306-0077cell, 907.644.2087 wk, bill.spencer@ (907) 441.7066 cell, 907.644.2014 wk, Kyle.Walker@

phone (907) 272-5264

500 W. 27th Avenue, Suite A Anchorage, AK 99503 mail@bce-

fax (907) 272-5214

Bratslavsky Consulting Engineers, Inc. CORDOVA FISH PASSAGE (FWS) PROJECT Minutes of Draft Geotech Report and Draft H&H Report Review Meeting March 5, 2019

Name Keith Mobley

Shelly McCoy

Tanya Bratslavsky George Uligan Betty Caudle

Agency/Company

Northern Geotechnical Engineers/Terra Firma Northern Geotechnical Engineers/Terra Firma BCE BCE BCE

Contact Info (907) 529-9180

(907) 771-9510

(907) 272-5264 / tanya@bce- (907) 272-5264 / George@bce- (907) 272-5264 / mail@bce-

Agenda:

1. Welcome/Introductions (5 min.) 2. Draft Geotech Report for all sites 3. Draft H&H report for Cop 43-45 4. Wrap-up/next steps (5 min.)

1. INTRODUCTIONS

After the introductions and roll call, Kate Morse from Copper River Watershed Project (CRWP) opened the meeting.

2. DRAFT GEOTECHNICAL REPORT REVIEW COMMENTS

Kate stated that because a required agreement wasn't in place yet, the Alaska Department of Transportation and Public Facilities (ADOT&PF) hasn't had a chance to review the report in detail to provide comments. They expect to have the agreement in place by the week of March 11 and will be able to provide comments about a week or two later. For today, the gathered stakeholders will go ahead and discuss the comments received so far and the next steps. We will incorporate ADOT&PF's comments when received.

Heather Hanson and Bill Rice from US Fish and Wildlife Service (FWS) provided their comments below.

1. USFWS strongly prefers culverts with closed bottoms for these projects for the following reasons: A. Concrete footers take longer to install than bottomed pipes and more accuracy is needed in survey B. Concrete footers have to be pre-fabricated and shipped from Anchorage. Based on FWS experience, poured-in-place footings are not recommended due to risk of flooding of the construction site(s) and amount of time involved to cure.

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Bratslavsky Consulting Engineers, Inc. CORDOVA FISH PASSAGE (FWS) PROJECT Minutes of Draft Geotech Report and Draft H&H Report Review Meeting March 5, 2019

C. Full-bottomed culverts act as one large footer and are at less risk (of forces that may shift concrete footers over time). Given that we may have significant water table variability and the less-competent foundations under some of these locations, going this route will reduce risk over the long term.

D. Based on FWS experience, full-bottomed culverts perform adequately in similar soils with 2 feet or less bedding material. It would be good to compare what ADOT&PF designs in the area have had in the past (for bedding).

Discussion:

While the relevant information is in the report, it needs to be revised for closed-bottom culverts as the option. The group concurred that closed-bottom culverts would be best for the reasons stated related to costs, soil types, settlement risks, earthquakes, low elevation of the sites, difficulties during construction, keeping excavation dry, etc. Closed-bottom culverts have been installed in other locations along the Copper River Highway with success, and FWS will provide some examples.

Types of Culverts

Bill Spencer with HDR stated that so far, 12'-15' span aluminum boxes have been reviewed (by HDR) for hydraulic capacity. An arch type culvert can also be considered, if that works best for a particular site. There are several ideas and design examples available.

Because of the low elevation between the stream bed and road, aluminum boxes work better. A box culvert will have much more capacity at lower head elevation. For larger rounded top, you would have to build the road up quite a bit, and water will just run around and go over the road somewhere else because it's so flat. As a result, it is difficult to develop the full hydraulic capacity of taller structures without raising a significant section of the road bed.

Per DOT, the aluminum box is their go-to design if they have limited cover (1' to 5') and a gravel road where you may have an inexperienced grader. We would need to build in a safety factor for minimum cover to account for the loss of cover during maintenance grading. If cover exceeds the maximum for aluminum box culverts, they go to an arch to get similar end area.

ADOT&PF will provide more detailed comments once they've had a chance to review the reports further.

Northern Tech commented that since they did not have any information on structures prior to their initial report, they went with bottomless culverts. They can certainly analyze the closed bottom culverts and asked for sample drawings.

Follow-up: After the call CRWP sent a follow-up question to ADOT&PF and USFWS regarding potential impact on groundwater upwelling with closed-bottom culverts, in particular at the highly groundwater-influenced Mile 25 site. Both entities responded that open-bottomed culverts were out of the scope of our budget in addition to the previous reasons stated for using closed-bottom culverts.

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Bratslavsky Consulting Engineers, Inc. CORDOVA FISH PASSAGE (FWS) PROJECT Minutes of Draft Geotech Report and Draft H&H Report Review Meeting March 5, 2019

Restraints or Anchors

Also recommended that we consider utilizing end restraints, which may be needed at crossings (based on the pipe size). Design will be for 100-year flood.

Per ADOT&PF, there is a chance of buoyancy because there are shallow embankments at different sites. So, the design needs to have some type of restraint to prevent flotations-whether it's a dead man, soil anchors, or another type. Not all sites may need restraints.

Per ADOT&PF, they are concerned about end restraint on the steeper pipes and on debris. There is a chance of creating a false anchor. ADOT&PF has gotten away from using headwalls, especially in fine grain soil, and prefer using deadmen. A typical deadman is a 3'x4' concrete weight that is banded to the pipe. They have been creating specifications for duckbill soil anchors, which are easier to install.

Per HDR, in other locations, a concrete toe wall can be installed underneath, and the culvert ends are bolted to it. So far, no failures, but they may not have enough history to determine if that is a good way to hold the pipe ends down.

The pipe itself has some embedded material inside some of it fairly large rocks, which will help to hold the culvert in place. While (we) haven't gotten to embedment yet in the discussion, it's a reasonable design parameter to consider.

Bedding Material

Per ADOT&PF, for bedding material--they have been using 2-inch minus, Type A, with less than 6% fines (#200 sieve) around the pipe, with Type E, 6-10% fines for the rest of the fill.

Cover

Heather asked ADOT&PF if there is a minimum additional cover beyond the manufacturer's minimum that they like to see. They responded that 1' additional cover would be their minimum. Typically, the manufacturer's minimum is 1.4' for aluminum box structures, so if it is extended by 1', we would end up with 2.5' of coverage and taper it off on the approaches.

HDR noted that for three sites, we'll end up with about 2' of cover, more will raise the road bed quite a bit. The concern is always about inexperienced operators shaving the top off when they grade the road. HDR has had past experience in placing a patch of asphalt on top of the culvert to help minimize the shaving of the cover.

ADOT&PF responded that they don't like to see small patches of asphalt because it is too hard to maintain. HDR commented that we can make tapers long enough on both ends so it doesn't end up being a bump in the road. A raised section that gets graded appropriately and not chopped off.

Heather commented that she recently found out that AASHTO load rating requirements for a bridge only allow a max of 5' of fill. Therefore, even if the manufacturer designs it for more fill, it

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Bratslavsky Consulting Engineers, Inc. CORDOVA FISH PASSAGE (FWS) PROJECT Minutes of Draft Geotech Report and Draft H&H Report Review Meeting March 5, 2019

wouldn't qualify for a bridge rating, which DOT requires. She asked if ADOT&PF could confirm that.

Soil

ADOT&PF noted that the earthwork section of the Geotech report, indicates that material that has "less than 15 percent passing the #200 sieve can be re-used as structural fill." This is higher than what they normally like to see as far as bedding and backfill around pipes. We like selected material Type A, which has a maximum of 6% passing the 200 sieve.

For areas where we do have finer grained soils with higher organic contents, it was suggested to consider putting geotextile layers in the foundation footer section. We normally have minimum of 1' of bedding under the pipes, but with poor subsoils bump it up to 2' with two different layers of geotech fabric reinforcement--one on the bottom and one in the center of that section.

Water Overflow at Sites

Kirsti Jurica from the CRWP commented that overflow has been due to beaver activity, not from flooding. In 2006 there were big floods, which overtopped the road; the whole road was under water in that area.

Bill spoke to the Forest Service rep at the site about silty water in the pond and along the Forest Service logging road (site 042). This would appear to indicate that Saddle Bag River has jumped its banks and was contributing silty glacial water to these drainages via the complex drainage network south of the river. He also spoke to Robbie with ADOT&PF maintenance. Robbie hasn't seen glacial washout problems and stated that most problems are caused by the beavers blocking the culverts and sending water over the road.

Per Bill, there is glacial water too, east of those sites, in a channel called the Spawning Channel, as the Forest Service refers it to. It has silty water that goes through there. Upland channels for 43, 44, and 45, also have silty water upstream.

Bill stated that there is good evidence that the Saddle Bag River floods its banks regularly, as often as every summer. It doesn't have a high bank to overcome as the river bed is only 6"-12" below the flood plain where it overtops into the forest.

Load Rating

Comment was made to look at the difference between 20, 25 and HL 93 or even heavier. Heather added that looking at prior designs in this area would be is a good place to start. (Follow up: Heather confirmed that the Mile 17 culvert was designed for HL-93).

Heather commented that the culvert manufacturer will design for those loads, it's in their specifications. But they can be modified. Giving the manufacturer actual loads that we anticipate is best. They generally utilize a standard soil bearing pressure for foundations of 4,000 psf, and for sidewalls - 2,000 psf. ADOT&PF now requires load ratings for structures over 10'.

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Bratslavsky Consulting Engineers, Inc. CORDOVA FISH PASSAGE (FWS) PROJECT Minutes of Draft Geotech Report and Draft H&H Report Review Meeting March 5, 2019

Per Keith from Northern Geotech, the culvert manufacturer needs to know soil pressures around the perimeter so the structure will resist those and utilize it for support. It goes both ways.

Jeff from ADOT&PF will look for a sample (from ADOT&PF) to include in the next draft of Geotech report. They have examples that may help. The ADOT&PF hydrology group doesn't provide load ratings. They defer to structural engineer, as they have a process to determine load rating. Typically, when we get closer to final design the load ratings are applied. They use HL93.

Another question was asked if we should consider moving the culvert locations. Bill stated that because these locations outfall into well-established downstream habitat channels, the culverts should remain in their current locations.

NEXT STEPS

Below are action items from today's meeting:

Provide a sketch so Geotech firm can get a better idea of lateral loadings to provide proper information.

USFWS will collect and analyze low flow data from sites Provide Geotech firm with sample drawings.

Upon receipt of sample drawings and other information discussed today, Northern Geotech, will revise the report based on additional information.

ADOT&PF to review the Geotech report and provide their detailed comments to Kate Morse.

ADOT&PF to confirm how their requirements match AASHTO bridge requirements. Determine which sites need anchoring of culverts Provide load rating and minimum cover with ADOT&PF's input.

3. DRAFT HYDROLOGY AND HYDRAULIC REPORT REVIEW COMMENTS

Heather Hanson from US Fish and Wildlife Service (USFWS) provided her comments below and Kate opened the discussion around Heather's comments on the draft H&H report.

1. Please include a record of the conversation with ADOT&PF O&M staff in this report regarding flood history at these sites.

Heather is aware that Bill Spencer with HDR had conversations with ADOT&PF O&M staff about the flood history at the project sites. She would like to see the conversations documented in the H&H report to make the record complete.

2. It would be good to compare the conservative flows that have been predicted here (in the report) with flows that do not include the additional "conservative" drainage areas and to see if they meet the 0.8 HW/D ratio requirements.

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Bratslavsky Consulting Engineers, Inc. CORDOVA FISH PASSAGE (FWS) PROJECT Minutes of Draft Geotech Report and Draft H&H Report Review Meeting March 5, 2019

Heather commented that the flows are pretty conservative, and they seem conservative for the drainage areas, which result in high flows at these sites, much higher than expected for this stream type. It would be good to compare the flow without those conservative drainage areas and see where we are. Maybe we end up with a two-fold approach where higher capacity is designed for the worst-case scenario, but the fish passage is designed for what we expect most of the time.

Bill Spencer from HDR responded that he intended to do that when he received Franklin's lower flow numbers. He plans to look at what is typically in those streams and design low flow channels inside the culverts for those flows. Probably size (on the high end) for flows we come up with conservative estimate. It's a `crap shoot' as a wide range of flows will potentially impact these sites. Streams are in big channels that indicate quite a bit of water has come down there. Maybe a long time ago and we don't need to design for that now? If you walk back up channels, they're good size.

Bill mentioned an earlier comment about relocating the culverts. He would advocate for leaving them in the same place because a lot of good habitat for fish are downstream from the structures. If we move them, we would either cut off water to those downstream channels and habitat would change/disappear also.

John Bennett from ADOT&PF asked if Bill would consider putting overflow pipe anchors if a stream does jump its bank and come into a different drainage. Maybe consider putting normal flow through the main pipe with the low flow channel so that we don't end up with shallow flows during normal years, but to add have extra capacity with the `flankers', so you do end up with higher than expected flows.

Bill responded that because this whole area is interconnected hydraulically on the upstream side, if the water comes up at all, it moves to a different culvert, and there are additional channels both east and west of the stream that we (HDR) have looked at: If water comes up significantly, it skips over to those as well. There are five structures within 1/2 mile of roadway that are all close to the same elevation, and have overflow capacity already built in to the system. In fact, the three pipes that we're replacing are all interconnected hydraulically within a few feet of each other. There is redundancy already built in.

Heather asked if we should leave the current pipes in place and put new pipe next to them. There would be a little channel reconstruction, but it would solve a couple of problems as far as diversion and additional capacity.

Bill responded that the fact that they are all tied together upstream makes diversion easy. Sandbag off the particular culvert we're working on and water will go to the adjacent one. Also, the existing structures are pretty beat up.

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Bratslavsky Consulting Engineers, Inc. CORDOVA FISH PASSAGE (FWS) PROJECT Minutes of Draft Geotech Report and Draft H&H Report Review Meeting March 5, 2019

One factor that should be discussed is the impact of the beaver activity. This is another reason why we advocate for fairly wide structures, which will quiet the water through the structure itself, so the beavers don't key in on the noise of flowing water and come to dam it up.

Bill advocates for putting new structures back where existing ones are for a number of reasons, including the downstream channel connects directly with existing structures and channels that were artificially created when the road was rebuilt back in the 1940's. They've re-grown nicely and have good habitat. He would hate to mess those up with diversion. Diversion should be an easy fix or chore on these sites. He would recommend leaving the existing culverts in place.

Jeff Stutzke with ADOT&PF asked if the goal is to maintain the current pond elevations.

Bill responded that yes, that would be the goal. A couple of the ponds right now are back watered from beaver dams downstream. So, you could almost do anything you want there, and you wouldn't change the elevation because the water is backwatered all the way from the next beaver dam below the road. But if the beaver dam breaks out, as they eventually do, he proposes putting some form of a sill that would maintain the backwater elevation on the upstream side. He asked Heather to weigh in on this topic.

Heather commented that she agrees with Bill. Although, it doesn't necessarily need to be the same elevation; it could be lowered a little bit. There's good habitat because of the backwatering conditions that we would want to keep. In the past, we have lowered the elevation a little bit just to make the crossing more fish friendly. The exact elevation target will depend on the profile.

3. We typically do some analysis comparing the bankfull discharge based on the channel characteristics to the predicted 2-year flood flow to see how these correlates. While we expect these are relic channels, it would be good to see if this analysis indicates that they are relic channels especially given the magnitude of the flood flow prediction.

Bill responded that we can certainly do that. Our initial approach was to combine all three basins together because they wander off into the forest and it is difficult to figure out what upstream basin goes to which culvert. The ground is so flat and there is lack of (inadequate) survey data. We could certainly take our 2-year flows, divide them by 3 and put those flows into each channel to see what kind of numbers we get.

Heather commented that she would concur with taking the total flow and not to try to look at individual basins for each pipe.

Bill commented that the center one, 44, is a slightly larger stream than the other two- both in terms of remnant channel and existing flows. HDR will provide that analysis.

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